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| [[Image:msigma.jpg|thumb|right|250px|Black hole mass plotted against velocity dispersion of stars in the galaxy bulge. Points are labelled by galaxy name;
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| all points in this diagram are for galaxies which exhibit a clear, [[Kepler's laws of planetary motion|Keplerian]] rise in velocity near the center, indicative of the presence of a central mass.
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| The M<math>-\sigma</math> relation is shown in blue.]]
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| The '''M–sigma''' (or M–σ) '''relation''' is an empirical correlation between the stellar [[velocity dispersion]] σ of a [[galaxy]] [[bulge (astronomy)|bulge]] and the mass M of the [[supermassive black hole]] at
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| the galaxy's center.
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| The M–σ relation was first presented in 1999 during a conference at the [[Institut d'astrophysique de Paris]] in [[France]]. The proposed form of the relation, which was called the "Faber-Jackson law for black holes", was <ref>{{cite conference
| | by Nas, is very fitting and the film agrees with it. It is very easy to customize plugins according to the needs of a particular business. The Word - Press Dashboard : an administrative management tool that supports FTP content upload 2. If you are using videos on your site then this is the plugin to use. After activating, you will find their website link and get the activation code from their website. <br><br>These folders as well as files have to copied and the saved. After all, Word - Press is free, many of the enhancements for Word - Press like themes and plugins are also free, and there is plenty of free information online about how to use Word - Press. There are number of web services that offer Word press development across the world. This is identical to doing a research as in depth above, nevertheless you can see various statistical details like the number of downloads and when the template was not long ago updated. Many times the camera is following Mia, taking in her point of view in almost every frame. <br><br>Just ensure that you hire experienced Word - Press CMS developer who is experienced enough to perform the task of Word - Press customization to get optimum benefits of Word - Press CMS. The only problem with most is that they only offer a monthly plan, you never own the software and you can’t even install the software on your site, you must go to another website to manage your list and edit your autoresponder. Those who cannot conceive with donor eggs due to some problems can also opt for surrogacy option using the services of surrogate mother. If you have any sort of concerns concerning where and ways to make use of [http://snipitfor.me/wordpress_backup_plugin_947255 wordpress backup plugin], you could contact us at our webpage. Enough automated blog posts plus a system keeps you and your clients happy. There are plenty of tables that are attached to this particular database. <br><br>If all else fails, please leave a comment on this post with the issue(s) you're having and help will be on the way. And, that is all the opposition events with nationalistic agenda in favor of the individuals of Pakistan marching collectively in the battle in opposition to radicalism. This allows for keeping the content editing toolbar in place at all times no matter how far down the page is scrolled. Word - Press is the most popular open source content management system (CMS) in the world today. Wordpress template is loaded with lots of prototype that unite graphic features and content area. <br><br>As a open source platform Wordpress offers distinctive ready to use themes for free along with custom theme support and easy customization. As a website owner, you can easily manage CMS-based website in a pretty easy and convenient style. Offshore Wordpress development services from a legitimate source caters dedicated and professional services assistance with very simplified yet technically effective development and designing techniques from experienced professional Wordpress developer India. In addition, Word - Press design integration is also possible. Customers within a few seconds after visiting a site form their opinion about the site. |
| | first = D. | last = Merritt | authorlink = David Merritt
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| | editor1-first = F. | editor1-last = Combes
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| | editor2-first = G. A. | editor2-last = Mamon
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| | editor3-first = V | editor3-last = Charmandaris
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| | title = Black holes and galaxy evolution
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| | booktitle = [http://adsabs.harvard.edu/abs/2000ASPC..197.....C Dynamics of Galaxies: from the Early Universe to the Present]
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| | publisher = [http://www.astrosociety.org/pubs/cs/csalpha.html#i Astronomical Society of the Pacific]
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| | pages = 221–232 | year = 1999 | isbn = 1-58381-024-2
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| | url = http://adsabs.harvard.edu/abs/2000ASPC..197..221M}}</ref>
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| :<math>
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| \frac{M}{10^8M_\odot} \approx 3.1\left(\frac{\sigma}{200~{\rm km}~{\rm s}^{-1}}\right)^4.
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| </math>
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| Publication of the relation in a refereed journal, by two groups, took place the following [[2000 in science|year]].<ref>Ferrarese, F. and [[David Merritt|Merritt, D.]] (2000), [http://adsabs.harvard.edu/abs/2000ApJ...539L...9F A Fundamental Relation between Supermassive Black Holes and Their Host Galaxies], ''The Astrophysical Journal'', '''539''', L9-L12</ref>
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| <ref>Gebhardt, K. et al. (2000), [http://adsabs.harvard.edu/abs/2000ApJ...539L..13G A Relationship between Nuclear Black Hole Mass and Galaxy Velocity Dispersion], ''The Astrophysical Journal'', '''539''', L13-L16</ref>
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| One recent study, based on a complete sample of published black hole masses in nearby galaxies,
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| <ref name=mcc2011>McConnell, N. J. et al. (2011), [http://adsabs.harvard.edu/abs/2011Natur.480..215M Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies], ''Nature'', '''480''', 215-218</ref> gives
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| :<math>
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| \frac{M}{10^8M_\odot} \approx 1.9\left(\frac{\sigma}{200~{\rm km}~{\rm s}^{-1}}\right)^{5.1}.
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| </math>
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| Earlier work had demonstrated a possible relationship between galaxy luminosity and black hole mass,<ref>Magorrian, J. et al. (1998), [http://adsabs.harvard.edu/abs/1998AJ....115.2285M The Demography of Massive Dark Objects in Galaxy Centers], ''The Astronomical Journal'', '''115''', 2285-2305</ref> but that relationship had a large scatter. The much smaller scatter of the M–σ relation is generally interpreted
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| to imply some source of mechanical [[feedback]] between the growth of supermassive black holes and the growth of galaxy bulges, although the source of this feedback is still uncertain.
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| Discovery of the M–σ relation was taken by many astronomers to imply that supermassive black holes are fundamental components of galaxies. Prior to about 2000, the main concern had been the simple detection of black holes, while afterward the interest changed to understanding the role of supermassive black holes as a critical component of galaxies. This led to the main uses of the relation to estimate black hole masses in galaxies that are too distant for direct mass measurements to be made, and to assay the overall black hole content of the Universe.
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| ==Origin==
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| The tightness of the M–σ relation suggests that some kind of feedback acts to maintain the connection between black hole mass and stellar velocity dispersion, in spite of processes like [[galaxy merger]]s and [[accretion (astronomy)|gas accretion]] that might be expected to increase the scatter over time.
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| One such mechanism was suggested by [[Joseph Silk]] and [[Martin Rees]] in 1998.<ref>Silk, J. and Rees, M. (1998), [http://adsabs.harvard.edu/abs/1998A%26A...331L...1S Quasars and galaxy formation], ''Astronomy and Astrophysics'', '''331''', L1-L4</ref> These authors proposed a model in which supermassive black holes first form via collapse of giant
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| gas clouds before most of the bulge mass has turned into stars. The black holes created in this way would then accrete and radiate, driving a wind which acts back on the accretion flow.
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| The flow would stall if the rate of deposition of mechanical energy into the infalling gas was large enough to unbind the protogalaxy in one [[crossing time]]. The Silk and Rees model predicts
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| a slope for the M–σ relation of α=5, which is approximately correct. However, the predicted normalization of the relation is too small by about a factor of one thousand. The reason is that there is far more energy released in the formation of a supermassive black hole than is needed to completely unbind the stellar bulge.
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| A more successful feedback model was first presented by [[Andrew King (astronomer)|Andrew King]] at the [[University of Leicester]] in 2003.<ref name=AKing>{{cite journal|last=King|first=Andrew|title=Black Holes, Galaxy Formation, and the MBH-σ Relation|journal=The Astrophysical Journal|year=2003|volume=596|pages=L27-L29|doi=10.1086/379143|url=http://adsabs.harvard.edu/abs/2003ApJ...596L..27K|arxiv = astro-ph/0308342 |bibcode = 2003ApJ...596L..27K }}</ref> In King's model, feedback occurs through momentum transfer, rather than energy transfer as in the case of Silk & Rees's model. A “momentum-driven flow” is one in which the gas cooling time is so short that essentially all the energy in the flow is in the form of bulk motion. In such a flow, most of the energy released by the black hole is lost to radiation, and only a few percent is left to affect the gas mechanically. King's model predicts a slope of α=4 for the M–σ relation, and the normalization is exactly correct; it is roughly a factor c/σ ≈ 10<sup>3</sup> times larger than in Silk & Rees's relation.
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| ==Importance==
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| Before the M–σ relation was discovered in 2000, a large discrepancy existed between black hole masses derived using three techniques.<ref name=MF01>Merritt, D. and Ferrarese, L. (2001), Relationship of Black Holes to Bulges [http://nedwww.ipac.caltech.edu/level5/March01/Merritt3/frames.html]</ref>
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| ''Direct,'' or dynamical, measurements based on the motion of stars or gas near the black hole seemed to give masses that averaged ~1% of the bulge mass (the "Magorrian relation"). Two other techniques—[[reverberation mapping]] in [[active galactic nuclei]], and the [[Soltan argument]], which computes the cosmological density in black holes needed to explain the [[quasar]] light—both gave a mean value of M/M<sub>bulge</sub> that was a factor ~10 smaller than implied by the Magorrian relation. The M–σ relation resolved this discrepancy by showing that most of the direct black hole masses published prior to 2000 were significantly in error, presumably because the data on which they were based were of insufficient quality to resolve the black hole's dynamical [[sphere of influence (astronomy)|sphere of influence]].<ref name=DEGN>{{cite book|last=Merritt|first=David|title=Dynamics and Evolution of Galactic Nuclei|year=2013|publisher=Princeton University Press|location=Princeton, NJ|isbn=9781400846122|url=http://openlibrary.org/works/OL16802359W/Dynamics_and_Evolution_of_Galactic_Nuclei}}</ref> The mean ratio of black hole mass to bulge mass is now believed to be approximately 1:1000.<ref>[[David Merritt|Merritt, D.]] and Ferrarese, L. (2001), [http://adsabs.harvard.edu/abs/2001MNRAS.320L..30M Black hole demographics from the M<math>-\sigma</math> relation], ''Monthly Notices of the Royal Astronomical Society'', '''320''', L30-L34</ref>
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| A common use of the M–σ relation is to estimate black hole masses in distant galaxies using the easily measured quantity σ. Black hole masses in thousands of galaxies have been estimated in this way. The M–σ relation is also used to calibrate so-called secondary and tertiary mass estimators, which relate the black hole mass to the strength of emission lines from hot gas in the nucleus or to the velocity dispersion of gas in the bulge.<ref>Peterson, B. (2008), [http://adsabs.harvard.edu/abs/2008NewAR..52..240P The central black hole and relationships with the host galaxy], ''New Astronomy Reviews'', '''52''', 240-252</ref>
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| The tightness of the M–σ relation has led to suggestions that ''every'' bulge must contain a supermassive black hole. However, the number of galaxies in which the effect of the black hole's gravity on the motion of stars or gas is unambiguously seen is still quite small.<ref>{{Citation
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| | last = Batcheldor
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| | first = D.
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| | title = The M-σ Relation Derived from Sphere of Influence Arguments
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| | journal = The Astrophysical Journal
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| | volume = 711
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| | pages = L108-L112
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| | year = 2010
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| | url = http://adsabs.harvard.edu/abs/2010ApJ...711L.108B |bibcode = 2010ApJ...711L.108B |doi = 10.1088/2041-8205/711/2/L108 |arxiv = 1002.1705 }}
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| </ref> It is unclear whether the lack of black hole detections in many galaxies implies that these galaxies do not contain black holes; or that their masses are significantly below the value implied by the M–σ relation; or that the data are simply too poor to reveal the presence of the black hole.<ref>Valluri, M. et al. (2004), [http://adsabs.harvard.edu/abs/2004ApJ...602...66V Difficulties with Recovering the Masses of Supermassive Black Holes from Stellar Kinematical Data], ''The Astrophysical Journal'', '''602''', 66-92</ref>
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| | |
| The smallest supermassive black hole with a well-determined mass has M≈10<sup>6</sup> solar masses.<ref name=DEGN/> The existence of black holes in the mass range 10<sup>4</sup> - 10<sup>6</sup> solar masses ("[[intermediate-mass black hole]]s") is predicted by the M–σ relation in low-mass galaxies, and the existence of intermediate mass black holes has been reasonably well established in a number of galaxies which contain [[active galactic nuclei]], although the values of M in these galaxies are highly uncertain.<ref>Ho, L. (2008), [http://adsabs.harvard.edu/abs/2008arXiv0803.2268H Nuclear activity in nearby galaxies], ''Annual Review of Astronomy & Astrophysics'', '''46''', 475-539</ref>
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| No clear evidence has been found for ultra-massive black holes with masses above 10<sup>10</sup> solar masses, although this may be an expected consequence of the observed upper limit to σ.<ref>Batcheldor, D. et al. (2007), [http://adsabs.harvard.edu/abs/2007ApJ...663L..85B How Special Are Brightest Cluster Galaxies?], ''The Astrophysical Journal'', '''663''', L85-L88</ref>
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| ==See also==
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| *[[Faber-Jackson relation]]
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| ==References==
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| {{reflist|colwidth=30em}}
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| {{Black holes}}
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| {{DEFAULTSORT:M-sigma relation}}
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| [[Category:Astrophysics]]
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| [[Category:Galaxies]]
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| [[Category:Supermassive black holes]]
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| [[Category:Unsolved problems in astronomy]]
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by Nas, is very fitting and the film agrees with it. It is very easy to customize plugins according to the needs of a particular business. The Word - Press Dashboard : an administrative management tool that supports FTP content upload 2. If you are using videos on your site then this is the plugin to use. After activating, you will find their website link and get the activation code from their website.
These folders as well as files have to copied and the saved. After all, Word - Press is free, many of the enhancements for Word - Press like themes and plugins are also free, and there is plenty of free information online about how to use Word - Press. There are number of web services that offer Word press development across the world. This is identical to doing a research as in depth above, nevertheless you can see various statistical details like the number of downloads and when the template was not long ago updated. Many times the camera is following Mia, taking in her point of view in almost every frame.
Just ensure that you hire experienced Word - Press CMS developer who is experienced enough to perform the task of Word - Press customization to get optimum benefits of Word - Press CMS. The only problem with most is that they only offer a monthly plan, you never own the software and you can’t even install the software on your site, you must go to another website to manage your list and edit your autoresponder. Those who cannot conceive with donor eggs due to some problems can also opt for surrogacy option using the services of surrogate mother. If you have any sort of concerns concerning where and ways to make use of wordpress backup plugin, you could contact us at our webpage. Enough automated blog posts plus a system keeps you and your clients happy. There are plenty of tables that are attached to this particular database.
If all else fails, please leave a comment on this post with the issue(s) you're having and help will be on the way. And, that is all the opposition events with nationalistic agenda in favor of the individuals of Pakistan marching collectively in the battle in opposition to radicalism. This allows for keeping the content editing toolbar in place at all times no matter how far down the page is scrolled. Word - Press is the most popular open source content management system (CMS) in the world today. Wordpress template is loaded with lots of prototype that unite graphic features and content area.
As a open source platform Wordpress offers distinctive ready to use themes for free along with custom theme support and easy customization. As a website owner, you can easily manage CMS-based website in a pretty easy and convenient style. Offshore Wordpress development services from a legitimate source caters dedicated and professional services assistance with very simplified yet technically effective development and designing techniques from experienced professional Wordpress developer India. In addition, Word - Press design integration is also possible. Customers within a few seconds after visiting a site form their opinion about the site.